Machines for the production of absorbent pads produce such pads by depositing hydrophilic particles or flakes on a support from which the pad is then transferred onto a substrate. The substrate with the absorbent pad deposited thereon is then used in the production of sanitary napkins, diapers, panties with absorbent inserts, fitted briefs, absorbent undergarments, and the like. The particles or flakes for this purpose are supplied from a source by an airstream flowing through a conduit to a flake pad former and depositor. The source of the flakes may be a fiber chopper to form particulate flake type material from a continuous web that is pulled off a supply reel.
In order to minimize adverse influences on the environment, including the work environment, and to protect the work place against excessive noise, it is now customary to separate the flake production facilities from the pad forming facilities. The two facilities are connected by a conduit in which a blower provides the necessary transporting air flow which intermixes with the produced flakes. Due to the length of the conduit, the internal friction between moving flakes and the inner surfaces of the conduit walls in combination with flow turbulences and static charges within the flake air mixture, there is a tendency to form nonuniform flake distributions and even flake clumps or bunched up balls of flakes. Such a nonuniform flake air flow is not suitable for the required homogenous flake distribution in the absorbent pads. A nonuniform flake distribution also adversely influences the stability of the flakes in a formed pad because flake bunches, although becoming part of the pad, are not properly bound into the pad, resulting in an inferior final product.
Efforts have been made heretofore to solve the problem of a uniform flake supply. For this purpose it is known to provide a positively driven milling rotor in the flake supply conduit. U.S. Pat. Nos. 1,834,309; 2,940,133; 2,940,134; 2,940,135; 3,886,629; and 4,375,447 relate to this technology. The provision of a positively driven milling rotor makes the supply conduit rather expensive. Besides, a substantial space is required for the installation of such rotors. The drive motor for these rotors must have a variable r.p.m. so that the r.p.m. can be adapted to the required through-put or through-flow of the flake air mixture per unit of time. Besides, such rotors produce undesirable air turbulences in the flow which again adversely affect the formation of a flake pad in which the flakes are uniformly distributed through the volume of the pad.
German Patent Publication DE 3,031,632 (Leifeld), published on Apr. 1, 1982, discloses an apparatus for cleaning and dedusting of textile fiber flakes. For this purpose, baffle grids or combs are positioned in the flow of the flake air mixture so as to function as filters or sieves which retain coarse particles while passing the airstream. Leifeld positions such a baffle comb (27, 27a) downstream of an injector nozzle (6, 7) as viewed in the flow direction. The purpose of these baffle combs is to deflect the flake air mixture toward sieves or grids (8, 8a) for the removal of dust from the flake air mixture.
German Patent Publication 1,111,933 (Chavannes et al.), published Jul. 27, 1961 discloses a method and apparatus for producing upholstery batting of cotton fibers or the like. The comminuted fibers travel on a conveyor belt that is air permeable through a chamber in which a synthetic material dust is injected into the cotton flake material This chamber is equipped with baffle plates (66) to diflect the airstream carrying the synthetic material dust in such a way that it must pass twice through the layer of batting and through the conveyor belt.
German Patent Publications DE 3,731,591 Al (Lucassen et al.), published on Apr. 6, 1989, discloses an apparatus for removing contaminations out of a fiber flow, especially spun fibers. For this purpose, guide combs (10, 11) are so arranged that they form an open rake (13, 14) which functions as a separator for the removal of the contaminations from the fiber flow. The flow of the fibers passes alongside of these combs or rakes.